Gear shift device

ABSTRACT

This gear shift device is used in a transmission of an engine, and is provided with: a shift drum that changes a speed change stage of the transmission according to a rotational position about an axis; an actuator having a driving shaft substantially orthogonal to the shift drum; a worm shaped barrel cam that is arranged parallel to the driving shaft of the actuator and that has a plurality of cam grooves on an outer circumference thereof; and a wheel gear that is coaxially fixed on the shift drum and that has a plurality of pins on an outer circumference thereof. At least a pair of each pin of the wheel gear and each cam groove of the barrel cam are engaged with each other, and the shift drum is rotated by the actuator via the barrel cam and the wheel gear, to thereby change the speed change stage of the transmission. The gear shift device is further with a detection device that detects a rotational position of the barrel cam.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Stage entry of International ApplicationNo. PCT/JP2007/068835, filed Sep. 27, 2007, which claims priority toJapanese patent Application No. P2006-270103, filed on Sep. 29, 2006,the disclosure of the prior applications is hereby incorporated in theirentirety by reference.

TECHNICAL FIELD

The present invention relates to a gear shift device to be used in atransmission of an engine of a vehicle or the like.

The present application is based on Japanese Patent Application, No.2006-270103, the contents of which axe incorporated herein by reference.

BACKGROUND ART

Heretofore, there has been a gear shift device in which a shift drumthat changes a speed change stage of a transmission according to arotational position about an axis, is rotated by an actuator with adriving shaft thereof arranged parallel to this shift drum, to therebychange the speed change stage of the transmission (for example, refer toPatent Document 1).

[Patent Document 1] Japanese Unexamined Patent Application, FirstPublication No. H11-82734

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

Incidentally, in the above conventional technique, in order to directlydetect the rotational position of the shift drum, a potentiometer isprovided on one end side thereof. However since this potentiometer iscomparatively expensive, there is the problem of increased cost.

Consequently, it is an object of the present invention to efficientlydetect the rotational position of the shift drum while keeping costdown, in a gear shift device used in a transmission of an engine of avehicle or the like.

Means for Solving the Problems

In order to resolve the above problems, the present invention employsthe following measures.

-   (1) That is to say, a gear shift device of the present invention is    used in a transmission of an engine, and is provided with: a shift    drum that changes a speed change stage of the transmission according    to a rotational position about an axis; an actuator having a driving    shaft substantially orthogonal to the shift drum; a worm shaped    barrel cam that is arranged parallel to the driving shaft of the    actuator and that has a plurality of cam grooves on an outer    circumference thereof, and a wheel gear that is coaxially fixed on    the shift drum and that has a plurality of pins on an outer    circumference thereof. At least a pair of each pin of the wheel gear    and each cam groove of the barrel cam are engaged with each other,    and the shift drum is rotated by the actuator via the barrel cam and    the wheel gear, to thereby change the speed change stage of the    transmission. The gear shift device is further with a detection    device that detects a rotational position of the barrel cam. The    detection device has a cam provided integral with an outer    circumference of the barrel cam.-   (2) There may be employed a configuration in which the detection    device has two independent sensors corresponding to the cam, which    are arranged with a predetermined phase difference along a    rotational direction of the barrel cam.

Effects of the Invention

According to the invention described in (1) above, by detecting therotational position of the shift drum from the rotational position ofthe worm shaped barrel cam, the rotational position of the shift drumcan be detected efficiently without using an expensive sensor.

In addition, by arranging the detection devices with a predeterminedphase difference in the barrel cam rotational direction, it is possibleto accurately detect if the barrel cam has rotated to the shift up sideor the shift down side, or if shift up or shift down has been completed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a right side view of a motorcycle in an embodiment of thepresent invention.

FIG. 2 is a right side view of an engine of the motorcycle.

FIG. 3 is a drawing showing a relevant section of the engine, being asectional view parallelly developed in the left-right direction.

FIG. 4 is a sectional view of a twin clutch transmission of the engine,

FIG. 5 is a configuration diagram of the twin clutch transmission.

FIG. 6 is a sectional view of a twin clutch of the twin clutchtransmission.

FIG. 7A is a sectional view corresponding to a part of FIG. 6, showing afirst modified example of an oil feed passage to a clutch disk of thetwin clutch.

FIG. 7B is a sectional view corresponding to a part of FIG. 6, showing asecond modified example of an oil feed passage to the clutch disk of thetwin clutch.

FIG. 8 is a side view of a bearing holder that holds, on the left sideof a mission case, ball bearings for supporting the left end section ofeach shaft of the twin clutch transmission.

FIG. 9 is a right side view of a hydraulic pressure cut-off device ofthe twin clutch of the twin clutch transmission.

FIG. 10 is a left side view of the engine.

FIG. 11A is a sectional view of a gear shift device of the engine.

FIG. 11B is a sectional view of the gear shift device of the engine.

FIG. 12A is a sectional view on A-A in FIG. 11A.

FIG. 12B is a sectional view on B-B in FIG. 11A,

FIG. 13A is a side view of a barrel cam of the gear shift device.

FIG. 13B is a development view of a cam groove on the outercircumference of the barrel cam.

FIG. 14 is a diagram illustrating ON and OFF of first and secondswitches with respect to rotational angle of the barrel cam.

FIG. 15A is a table illustrating ON and OFF of the above respectiveswitches with respect to rotational regions of the barrel cam.

FIG. 15B is a table showing torque of a barrel cam driving motor withrespect to rotational regions of the barrel cam.

FIG. 16 is a drawing showing a modified example of an arrangement of thefirst and second sensors, being a sectional view corresponding to FIG.12A and FIG. 12B.

FIG. 17A is a graph showing rotational angle and angular velocity of ashift drum with respect to barrel cam rotational angle of the gear shiftdevice, showing a case where the cam grooves are connected via a curvesection.

FIG. 17B is a graph showing rotational angle and angular velocity of ashift drum with respect to barrel cam rotational angle of the gear shiftdevice, showing a case where the cam grooves are connected but not via acurve section.

FIG. 18 is a drawing showing a modified example of a solenoid valvearrangement in the twin clutch transmission, being a side viewcorresponding to FIG. 10.

FIG. 19 is a drawing showing another modified example of a solenoidvalve arrangement in the twin clutch transmission, being a side viewcorresponding to FIG. 10.

FIG. 20 is a right side view of the motorcycle with solenoid valvesarranged therein as shown in FIG. 19.

DESCRIPTION OF THE REFERENCE SYMBOLS

-   -   1 Motorcycle (saddle riding type vehicle)    -   13 Engine    -   23 Twin clutch transmission (transmission)    -   24 a Shift drum    -   41 Gear shift device    -   121 Fin gear (wheel gear)    -   121 a Pin    -   122 Barrel cam    -   124 Electric motor (actuator)    -   125 Driving shaft    -   129 Cam groove    -   131 Switch cam (detection device)    -   133 First switch (detection device)    -   134 Second switch (detection device)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereunder an embodiment of the present invention is described, withreference to the drawings. In the following description, orientationsincluding front-rear/left-right orientations are the same asorientations in a vehicle unless particularly mentioned. Moreover, inthe drawings, the arrow FR points to the front side of the vehicle, thearrow LH points to the left side of the vehicle, and the arrow UP pointsto the upside of the vehicle.

As shown in FIG. 1, an upper section of a front fork 3 that pivotallysupports a front wheel 2 of a motorcycle (saddle riding type vehicle) 1,is steerably pivot-supported via a steering stem 4, on a head pipe 6 ofa front end section of a vehicle body frame 5. A main frame 7 extendsrearward from the head pipe 6 and connects with a pivot plate 8. On thepivot plate 8 there is vertically swingably pivot-supported the frontend section of a swing arm 9, and on the rear end section of this swingarm 9 there is pivotally supported a rear wheel 11. Between the swingarm 9 and the vehicle body frame 5 there is interveningly provided acushion unit 12. On the vehicle body frame 5 there is mounted an engine(internal combustion engine) 13 that serves as a motor of the motorcycle1.

Also making reference to FIG. 2, the engine 13 is a parallelfour-cylinder engine with a crank shaft axis C1 thereof along thevehicle width direction (left-right direction), and on a crank case 14thereof there is provided a cylinder section 15 standing upright. To therear section of this cylinder section 15 there is connected a throttlebody 16 of an induction system, and to the front section there isconnected an exhaust pipe 17. Inside the cylinder section 15 there arereciprocatably fitted pistons 18 corresponding to respective cylinders,and reciprocation of these pistons 18 is converted, via connecting rods19, to rotation of a crank shaft 21.

Also making reference to FIG. 3, to the rear of the crank case 14 thereis integrally connected a mission case 22, and inside this mission case22 there are housed a twin clutch transmission 23 and a change mechanism24. The right side section of the mission case 22 serves as a clutchcase 25, and inside this clutch case 25 there is housed a twin clutch 26of the twin clutch transmission 23. On the mission case 22 there isarranged a starter motor 27 (refer to FIG. 3). A rotational force of thecrank shaft 21 is output, via the twin clutch transmission 23, to theleft side of the mission case 22, and is then transmitted, for examplevia a chain type power transmission mechanism, to the rear wheel 11.

As shown in FIG. 2 the engine 13 is configured such that three mainshafts, namely the crank shaft 21, a main shaft 28 in the twin clutchtransmission 23 parallel to the crank shaft 21, and a counter shaft 29,are in a triangular arrangement. Specifically, the axes C1 and C2 of thecrank shaft 21 and the main shaft 28 are arranged on a rear-risingupper/lower dividing plane B in the crank case 14, and the axis C3 ofthe counter shaft 29 is arranged below the dividing plane B and on therear side on the crank shaft 21. Thus, the front-rear length of theengine 13 is reduced, and the level of freedom of the layout of theengine 13 can be increased. On the rear side and slightly upper side ofthe main shaft 28 there is arranged the change mechanism 24.

As shown in FIG. 3, on the inner side of the lower section of the crankcase 14 there are arranged first and second oil pumps 31 and 32 thatshare a driving shaft 33 along the left-right direction. The first oilpump 31 serves to pressure-feed oil into respective sections in theengine, and a discharge port thereof is connected, via a main oil feedpassage 34, to a main oil gallery (not shown in the drawing). On theother hand, the second oil pump 32 serves to generate hydraulic pressurefor operating the twin clutch 26, and a discharge port thereof isconnected to an oil feed passage 35 to the twin clutch 26. Referencesymbol 37 denotes a strainer that extends downward from the respectiveoil pumps 31 and 32 to be immersed in engine oil in an oil pan 36 belowthe crank case 14, and reference symbol 38 denotes a water pump that isarranged on the right side of the lower section of the crank case 14 andthat has a driving shaft coaxial with the respective oil pumps 31 and32.

Here, as shown in FIG. 5, the motorcycle 1 is provided with an automatictransmission system primarily including: the twin clutch transmission 23provided so as to be connected to the engine 13; a gear shift device 41in which a driving mechanism 39 is provided in the change mechanism 24;and an electronic control unit (ECU) 42 that controls operations of thetwin clutch transmission 23 and the gear shift device 41.

Also making reference to FIG. 4, the twin clutch transmission 23 isprovided with the main shaft 28 of a dual structure having inner andouter shafts 43 and 44; the counter shaft 29 arranged parallel with thismain shaft 28; a speed change gear set 45 arranged between the mainshaft 28 and the counter shaft 29; the twin clutch 26 coaxially arrangedon the right end section of the main shaft 28; and a hydraulic pressuresupply device 46 that supplies hydraulic operating pressure to this twinclutch 26. Hereunder, a collective body including the main shaft 28, thecounter shaft 29, and the speed change gear set 45 may be referred to asa transmission 47.

The main shaft 28 has a configuration where the right side section ofthe inner shaft 43 extending in the left-right direction of the missioncase 22 is inserted through inside the outer shaft 44. On the outercircumferences of the inner and outer shafts 43 and 44 there aredistributedly-arranged driving gears 48 a to 48 f for six speeds in thespeed change gear set 45. On the other hand, on the outer circumferenceof the counter shaft 29 there are arranged driven gears 49 a to 49 f forsix speeds in the speed change gear set 45. The respective driving gears48 a to 48 f and the driven gears 49 a to 49 f mesh with each other ateach of the speed stages, respectively forming speed change gear pairs45 a to 451 that correspond to the respective speed stages. Each of thespeed change gear pairs 45 a to 45 f is such that the reduction gearratio becomes smaller (becomes a higher speed gear) in order from thefirst speed to the sixth speed.

The twin clutch 26 includes hydraulic pressure type first and seconddisk clutches (hereunder, may be referred to simply as clutches) 51 aand 51 b arranged coaxially adjacent to each other, and the inner andouter shafts 43 and 44 are respectively coaxially connected to theseclutches 51 a and 51 b. It is possible to individually engage anddisengage the respective clutches 51 a and 51 b with thepresence/absence of hydraulic pressure supply from the hydraulicpressure supply device 46.

The change mechanism 24 moves a plurality of shift forks 24 b withrotation of a shift drum 24 a arranged parallel to the respective shafts28 and 29, to thereby switch the speed change gear pairs to be used forpower transmission to the counter shaft 29. On the left end section ofthe shift drum 24 a there is arranged the driving mechanism 39.Reference symbol S1 in FIG. 5 denotes a sensor (a pair of switch cams131 and a first switch 133 or second switch 134 for detecting rotationalangle of a barrel cam 122 to be described later) that detects an amountof operation of the driving mechanism 39 for detecting the speed stageof the transmission 47.

The electronic control unit (ECU) 42, based in addition to informationfrom the above respective sensors, on information from a throttle gripopening sensor T1, a throttle valve opening sensor T2 of a throttle body16, a side-stand (or center-stand) housing sensor SS, and for example, amode switch SW1 and a shift switch SW2 provided on a handlebar, controlsoperations of the twin clutch transmission 23 and the gear shift device41 to thereby change the speed stage (shift position) of thetransmission 47.

A speed change mode to be selected by the mode switch SW1 includes afull automatic mode in which speed stages are automatically switchedbased on vehicle raveling information such as vehicle speed and enginerevolution, and a semi-automatic mode in which speed stages are switchedonly by operations of the shift switch SW2 based on the rider'sintention. The current speed change mode and speed stage areappropriately displayed on a meter device M provided in the vicinity ofthe handlebar for example. The ECU 42 appropriately shares informationfrom the respective sensors with an ECU 42 a for a fuel injection deviceand an ECU 42 b for an anti-locking brake device.

Moreover one of the respective clutches 51 a and 51 b is engaged and theother one is disengaged, and power transmission is carried out with useof any one of the speed change gear pairs connected to one of the innerand outer shafts 43 and 44, while a speed change gear pair to be usednext is pre-selected from among the speed change gear pairs to beconnected to the other one of the inner and outer shafts 43 and 44. Fromthis state, one of the respective clutches 51 a and 51 b is disengagedand the other one is engaged, to thereby switch to power transmissionwith use of the pre-selected speed change gear pair, and thus thetransmission 47 is shifted up or shifted down. Reference symbol S2 inFIG. 5 denotes a vehicle speed sensor that detects rotation speed of themain shaft 28 (that detects rotation speed of the driving gear 48 e thatmeshes with the driven gear 49 e that integrally rotates with thecounter shaft 29) for vehicle speed detection, reference symbol S3denotes a rotation speed sensor that detects rotation speed of a primarydrive 58 a for engine revolution speed (crank shaft rotation speed)detection, and reference symbols S4 and S5 respectively denote rotationspeed sensors that detect rotation speed of the inner and outer shafts43 and 44 (that detect rotation speed of the driven gears 49 c and 49 dthat mesh with the integrally rotating respective driving gears 48 c and48 d of the inner and outer shafts 43 and 44).

As shown in FIG. 6, the twin clutch 26 is such that inside the clutchcase 25 (inside the hydraulic chamber), the first clutch 51 a for oddgears is arranged on the right side (outer side in the vehicle widthdirection) and the second clutch 51 b is arranged on the left side(inner side in the vehicle width direction). The respective clutches 51a and 51 b are wet type multiplate clutches having a plurality of clutchplates alternately superposed in the axial direction thereof. The rightside section of the clutch case 25 is a clutch cover 69 that isattachably and detachably fixed with a plurality of bolts (refer to FIG.3 and FIG. 4), and the first clutch 51 a is arranged toward a rightouter wall 69 a side of this clutch cover 69.

The respective clutches 51 a and 51 b are hydraulic pressure typeclutches that displace pressure plates 52 a and 52 b in the axialdirection with externally supplied hydraulic pressure to thereby exert apredetermined engagement force, and are provided with: return springs 53a and 53 b that bias the pressure plates 52 a and 52 b to the clutchdisengagement side; engagement side hydraulic chambers 54 a and 54 b,that give the pressure plates 52 a and 52 b a pressing force towards theclutch engagement side; and disengagement side hydraulic chambers 55 aand 55 b that give the pressure plates 52 a and 52 b a pressing forcetowards the clutch disengagement side and compensate a pressure for thereturning action thereof (that cancel an amount of the pressing forceincreased by the centrifugal force of the respective clutches 51 a and51 b). In the disengagement side hydraulic chambers 55 a and 55 b,hydraulic pressure from the first oil pump 31 constantly operates in acomparatively low pressure state. On the other hand, a comparativelyhigh hydraulic pressure from the hydraulic pressure supply device 46 canbe supplied into the engagement side hydraulic chambers 54 a and 54 b.

Also making reference to FIG. 4, the respective clutches 51 a and 51 bare configured so as to share a single clutch outer 56 and havesubstantially the same diameter. The clutch outer 56 is of abottom-ended cylinder shape that opens to the right, and on the leftside of the interior thereof there is arranged a clutch center 57 a forthe first clutch 51 a, and on the right side of the interior thereofthere is arranged a clutch center 57 b for the second clutch 51 b.

On the bottom section left side of the clutch outer 56 there isconnected via a spring damper a primary driven gear 58, and the primarydrive gear 58 a of the crank shaft 21 meshes with this primary drivengear 58. The clutch outer 56 is such that a hub section 56 a thereof isrelatively and rotatably supported via a needle bearing on the mainshaft 28 (outer shaft 44), and it integrally rotates together withrotation of the crank shaft 21. On the left side of the primary drivengear 58 in the hub section 56 a of the clutch outer 56, there isintegrally and rotatably provided a driving sprocket 56 b for drivingthe respective oil pumps 31 and 32. On the inner circumferential rightside and on the inner circumferential left side of the outer wallsection of the clutch outer 56, there are supported respectively aplurality of clutch plates 61 a for the first clutch 51 a and aplurality of clutch plates 61 b for the second clutch 51 b so as to beunable to relatively rotate.

The clutch center 57 a of the first clutch 51 a is such that a centercylinder section 62 a thereof is spline-fitted to the right end sectionof the inner shaft 43 that projects to the right from the right endsection of the outer shaft 44, and is integrally fixed by a lock nut 78.The left side section of the clutch center 57 a is a flange section 64 athat expands towards the inner circumference of the outer wall sectionof the clutch outer 56. On the radial direction intermediate section ofthe flange section 64 a there is provided an inner wall section 65 aprojecting to the right, and on the outer circumference of this innerwall section 65 a there is supported a plurality of clutch disks 66 a soas to be unable to relatively rotate. The respective clutch disks 66 aand the respective clutch plates 61 a are arranged so as to bealternately superposed in the clutch shaft direction.

On the right side of the flange section 64 a there is opposinglyarranged the pressure plate 52 a with a predetermined gap therebetween,and between the outer circumference side of this pressure plate 52 a andthe outer circumference side of the flange section 64 a there arearranged in a laminated state the respective clutch plates 61 a and therespective clutch disks 66 a. Between the inner circumference side ofthe pressure plate 52 a and the inner circumference side of the flangesection 64 a, there is formed the disengagement side hydraulic chamber55 a, and there is arranged the return spring 53 a that biases thepressure plate 52 a to the right (to the side distanced from the flangesection 64 a, to the clutch disengagement side).

On the right side of the inner circumference side of the pressure plate52 a, there is opposingly arranged a support flange section 67 aintegrally provided on the outer circumference of the center cylindersection 62 a, and between this support flange section 67 a and the innercircumference side of the pressure plate 52 a there is formed theengagement side hydraulic chamber 54 a.

Here, the flange section 64 a is configured with the inner and outercircumference sides separate from each other, and between these innerand outer separated bodies there is interveningly provided a dampermember 59 made from an elastic body such as rubber. As a result, shockabsorbing performance at the time of clutch disengagement of the firstclutch 51 a is increased.

On the other hand, the clutch center 57 b of the second clutch 51 b issuch that a center cylinder section 62 b thereof is spline-fitted to theright end section of the outer shaft 44 and is integrally fixed by alock nut 79. The left side section of the clutch center 57 b is a flangesection 64 b that expands towards the inner circumference of the outerwall section of the clutch outer 56. On the radial directionintermediate section of the flange section 64 b there is provided aninner wall section 65 b projecting to the right and on the outercircumference of this inner wall section 65 b there is supported aplurality of clutch disks 66 b so as to be unable to relatively rotate.The respective clutch disks 66 b and the respective clutch plates 61 bare arranged so as to be alternately superposed in the clutch shaftdirection.

On the right side of the flange section 64 b there is opposinglyarranged the pressure plate 52 b with a predetermined gap therebetween,and between the outer circumference side of this pressure plate 52 b andthe outer circumference side of the flange section 64 a there arearranged in a laminated state the respective clutch plates 61 b and therespective clutch disks 66 b. Between the inner circumference side ofthe pressure plate 52 b and the inner circumference side of the flangesection 64 b, there is formed the disengagement side hydraulic chamber55 b, and there is arranged the return spring 53 b that biases thepressure plate 52 b to the right (to the side distanced from the flangesection 64 b, to the clutch disengagement side).

On the right side of the inner circumference side of the pressure plate52 b, there is opposingly arranged a support flange section 67 bintegrally provided on the outer circumference of the center cylindersection 62 b, and between this support flange section 67 b and the innercircumference side of the pressure plate 52 b there is formed theengagement side hydraulic chamber 54 b.

The flange section 64 b is configured such that the inner and outercircumference sides thereof are integrated with each other. However, aswith the flange 64 a, it may be separately configured with a dampermember interveningly provided therein. Here, the respective clutches 51a and 51 b are such that the thicknesses of the respective clutch plates61 a and 61 b are made different to each other (the clutch plate 61 a ofthe first clutch 51 a is made thicker than the clutch plate 61 b of thesecond clutch 51 b), to thereby have different thermal capacities whilehaving the same number of disks and the same diameter.

In an engine stop state (stop state of the respective oil pumps 31 and32), the respective clutches 51 a and 51 b, with the biasing forces ofthe respective return springs 53 a and 53 b, displace the pressureplates 52 a and 52 b to the right, thereby giving a clutch disengagementstate where friction engagement between the respective clutch plates 61a and 61 b and the respective clutch disks 66 a and 66 b has beendisengaged. Moreover, even when the engine is being operated, in a statewhere supply of hydraulic pressure from the hydraulic pressure supplydevice 46 is stopped, biasing forces of the return springs 53 a and 53 band hydraulic pressure of the respective disengagement side hydraulicchambers 55 a and 55 b act on the pressure plates 52 a and 52 b, therebygiving a clutch disengagement state similar to that mentioned above.

On the other hand, in the first clutch 51 a, in a state where the engineis being operated and a comparatively high hydraulic pressure from thehydraulic pressure supply device 46 is being supplied into theengagement side hydraulic chamber 54 a, the pressure plate 52 a isdisplaced to the left (to the flange section 64 a side, the clutchengagement side) against the hydraulic pressure of the disengagementside hydraulic chamber 55 a and the biasing force of the return spring53 a, so as to clamp the respective clutch plates 61 a and therespective clutch disks 66 a, causing them to friction-engage with eachother. As a result, this gives a clutch engagement state where torquetransmission between the clutch outer 56 and the clutch center 57 a ispossible.

Similarly, in the second clutch 51 b, in a state where the engine isbeing operated and a comparatively high hydraulic pressure from thehydraulic pressure supply device 46 is being supplied into theengagement side hydraulic chamber 54 b, the pressure plate 52 b isdisplaced to the left (to the flange section 64 b side, the clutchengagement side) against the hydraulic pressure of the disengagementside hydraulic chamber 55 b and the biasing force of the return spring53 b, so as to clamp the respective clutch plates 61 b and therespective clutch disks 66 b, causing them to friction-engage with eachother. As a result, this gives a clutch engagement state where torquetransmission between the clutch outer 56 and the clutch center 57 b ispossible.

When from the clutch engagement state of the respective clutches 51 aand 51 b, hydraulic pressure supply to the engagement side hydraulicchambers 54 a and 54 b is stopped, the hydraulic pressure of thedisengagement side hydraulic chambers 55 a and 55 b and the biasingforces of the return springs 53 a and 53 b cause the pressure plates 52a and 52 b to displace to the left, thereby giving the above mentionedclutch disengagement state where friction engagement between therespective clutch plates 61 a and 61 b and the respective clutch disks66 a and 66 b has been disengaged, and torque transmission is therebymade impossible between the clutch outer 56 and the clutch centers 57 aand 57 b. As described above, with use of the hydraulic pressure of thedisengagement side hydraulic chambers 55 a and 55 b in addition to thebiasing forces of the return springs 53 a and 53 b, it is possible, evenif hydraulic pressure remains within the engagement side hydraulicchambers 54 a and 54 b due to centrifugal force, to reliably move thepressure plates 52 a and 52 b.

Here, the engine oil supplied into the disengagement side hydraulicchambers 55 a and 55 b of the respective clutches 51 a and 51 b isguided to the outside of the hydraulic chambers through oil passages 68a and 68 b formed in the inner wall sections 65 a and 65 b, and issupplied to the respective clutch plates 61 a and 61 b and therespective clutch disks 66 a and 66 b on the outer circumference of theinner wall sections 65 a and 65 b. Thus, by releasing the operating oilwithin the disengagement side hydraulic chambers 55 a and 55 b, it ispossible to maintain the inside of the disengagement side hydraulicchambers 55 a and 55 b at a predetermined low pressure while enhancingthe lubricating and cooling performance of the respective clutch plates61 a and 61 b and the respective clutch disks 66 a and 66 b in thedisengagement state.

The above mentioned oil passages 68 a and 68 b may be formed as an oilpassage 168 as shown for example in FIG. 7A, substantially perpendicularto the clutch shaft direction, in the flange section 64 a of the clutchcenter 57 a, or they may be formed as an oil passage 268 as shown inFIG. 73, substantially parallel to the clutch shaft direction, in theflange section 64 a of the clutch center 57 a. FIG. 7A and FIG. 7B showthe first clutch 57 a; however, a similar modified example may beapplied to the second clutch 51 b.

As shown in FIG. 4, the transmission 47 is a constant mesh typetransmission in which the driving gears 48 a to 48 f that correspond tothe respective speed stages are constantly meshed with the driven gears49 a to 49 f. The respective gears are broadly classified as free gearsthat can freely rotate relative to the shaft, and sliding gears that arespline-fitted to the shaft. By appropriately sliding an arbitrarysliding gear with the change mechanism 24, they enable powertransmission with use of a speed change gear pair that corresponds toany one of the speed stages.

In the interior of the main shaft 28 (inner shaft 43) and the countershaft 29, there are respectively formed primary oil feed passages 71 and72, through which hydraulic pressure from the first oil pump 31 can besupplied, and engine oil is appropriately supplied through these primaryoil feed passages 71 and 72 to the speed change gear set 45.

The inner shaft 43 the main shaft 28 is a comparatively thick-walledhollow cylinder shape, and this inner shaft 43 is relatively rotatablyinserted, via a needle bearing, into the comparatively thick-walledcylinder-shaped outer shaft 44.

The left end section of the inner shaft 43 reaches a left outer wall 22a of the mission case 22 and is rotatably supported on this left outerwall 22 a via a ball bearing 73. The left end section of the inner shaft43 projects to the left of the ball bearing 73. On this projectedsection there is threaded a lock nut 74. This lock nut 74 and the stepsection of the inner shaft 43 tighten and fix the inner race of the ballbearing 73.

Making reference also to FIG. 8, on the left outer wall 22 a of themission case 22 there is fixed with a bolt from the inside of the case,a holder plate 75, and this holder plate 75 and the step section of theleft outer wall 22 a of the mission case 22 tighten and fix the outerrace of the bail bearing 73. As a result, the axial directionpositioning of the inner shaft 43 is determined via the ball bearing 73.The left end section of the inner shaft 43 passes through the left outerwall 22 a of the mission case 22. However, the through hole in this leftouter wall 22 a (supporting hole of the ball bearing 73) for the innershaft 43 is oil-tightly closed from the outside of the mission case 22by a sealing cap 76.

The right end section of the inner shaft 43 passes through a right sidewall 22 b of the mission case 22 (which is also the left side wall ofthe clutch case 25) and reaches the vicinity of the right outer wall 69a of the clutch case 25 (clutch cover 69), and to this right end sectionthere is attached the clutch center 57 a of the first clutch 51 a so asto be unable to relatively rotate. The left-right-intermediate sectionof the inner shaft 43 is rotatably supported, via the outer shaft 44 anda ball bearing 77, on the right side wall 22 b of the mission case 22.On the right end section of the inner shaft 43 there is threaded thelock nut 78. This lock nut 78 and the thrust receiving section of theinner shaft 43 tighten and fix the center cylinder section 62 a of theclutch center 57 a.

The outer shaft 44 is shorter than the inner shaft 43, and the left endsection thereof terminates at the left-right-intermediate section of themission case 22. In a part on the outer shaft 44 positioned to the leftfrom the ball bearing 77, there are supported the driving gears 48 b, 48d, and 48 f corresponding to the even stages (second speed, fourthspeed, and sixth speed) in the speed change gear set 45, in order fromthe left side for; the fourth speed, the sixth speed, and the secondspeed. On the other hand, in a part on the inner shaft 43 positioned tothe left from the left end section of the outer shaft 44, there aresupported the driving gears 48 a, 48 c, and 48 e corresponding to theodd stages (first speed, third speed, and fifth speed) in the speedchange gear set 45, in order from the left side for; the first side, thefifth speed, and the third speed.

The right end section of the outer shaft 44 passes through the rightside wall 22 b of the mission case 22 and reaches the inside of theclutch case 25, and to this right end section there is attached theclutch center 57 b of the second clutch 51 b so as to be unable torelatively rotate. In a part on the outer shaft 44 between the clutchcenter 57 b and the ball bearing 77, there is relatively and rotatablysupported the clutch outer 56 (and the primary driven gear 58).

On the right end section of the outer shaft 44 there is threaded thelock nut 79. This lock nut 79 and the thrust receiving section of theouter shaft 44 tighten and fix the inner race of the ball bearing 77,the distance collar on the inner side of the hub section 56 a of theclutch outer 56, and the center cylinder section 62 b of the clutchcenter 57 b.

On the right side wall 22 b of the mission case 22 there is fixed with abolt from the case outer side (clutch case 25 side), a holder plate 81,and this holder plate 81 and the step section of the right side wall 22b of the mission case 22 tighten and fix the outer race of the ballbearing 77. As a result, axial direction positioning with respect to themission case 22 in the outer shaft 44 is determined via the ball bearing77.

The left side section of the counter shaft 29 is rotatably supported,via a ball bearing 82, on the left outer wall 22 a of the mission case22. The left end section of the counter shaft 29 projects to the left ofthe ball bearing 82, and on this left end section there is spline-fittedand fixed with a bolt, a driving sprocket 83 in the mechanism fortransmitting power to the rear wheel 11. The periphery of the drivingsprocket 83 and the sealing cap 76 is covered by a sprocket cover 84 tobe attached to the left side of the mission case 22. The outer race ofthe ball bearing 82 is tightened and fixed by the holder plate 75 andthe step section of the left outer wall 22 a of the mission case 22(refer to FIG. 8).

The right side section of the counter shaft 29 is rotatably supported,via a ball bearing 86, on the right side wall 22 b of the mission case22. On the right side wall 22 b of the mission case 22 there is fixedwith a bolt, a holder plate 87, and this holder plate 87 and the stepsection of the right side wall 22 b of the mission case 22 tighten andfix the outer race of the ball bearing 86. In a part on the countershaft 29 positioned between the respective ball bearings 82 and 86,there are supported, in order as with that of the respective drivinggears 48 a to 48 f, the driven gears 49 a to 49 f corresponding to therespective speed change stages in the speed change gear set 45.

Here, the transmission 47 is configured as a cartridge type that can betaken out integrally with the right side wall 22 b of the mission case22, to the outside of the mission case 22.

The right side wall 22 b of the mission case 22 is configured so as tobe attachable/detachable with a plurality of bolts to a case main body,and functions as a mission holder in which this right side wall 22 bretains the transmission 47 as a single unit.

Roughly describing the manner of taking out this transmission 47 to theoutside of the mission case 22, first, on the case left side, thesprocket cover 84 and the sealing cap 76 are detached, and the lock nut74 is detached from the left end section of the main shaft 28, whiledetaching the driving sprocket 83 from the left end section of thecounter shaft 29. Subsequently, having detached the clutch cover 69 onthe case right side and detached the lock nut 78 and the clutch center57 a from the inner shaft 43, the lock nut 79, the clutch center 57 b,the clutch outer 56 and so forth are detached from the outer shaft 44,and then the transmission 47 as well as the mission holder are drawn outto the right of the mission case 22. At this time, the ball bearing 73that supports the left end section of the main shaft 28 and the ballbearing 82 that supports the left end section of the counter shaft 29remain retained on the left outer wall 22 a of the mission case 22 bythe holder plate 75.

As shown in FIG. 5, the hydraulic pressure supply device 46 primarilyincludes: the respective oil pumps 31 and 32; the primary oil feedpassage 34 that extends from the discharge port of the first oil pump31; a first oil filter 88 arranged in this primary oil feed passage 34;the oil feed passage 35 that extends from the discharge port of thesecond oil pump 32; a second oil filter 89 arranged in this oil feedpassage 35; first and second solenoid valves (proportional type linearsolenoid valves) 91 a and 91 b to which the downstream side of the oilfeed passage 35 is connected; first and second oil feed passages 92 aand 92 b that extend from these solenoid valves 91 a and 91 b to theengagement side hydraulic chambers 54 a and 54 b of the respectiveclutches 51 a and 51 b; and an hydraulic pressure cut-off device 94 thatreturns the hydraulic pressure from the second oil pump 32 to the oilpan 36 when starting the engine.

Reference symbols 56 and 57 denote a hydraulic pressure sensor and anoil temperature sensor provided in the primary oil feed passage 34 todetect hydraulic pressure and oil temperature, reference symbols R1 andR2 denote relief valves provided on oil passages branched from theprimary oil feed passage 34 and the oil feed passage 35 to operate whena predetermined hydraulic pressure is exceeded, and reference symbols S8and 59 denote hydraulic pressure sensors provided on the respective oilfeed passages 92 a and 92 b to detect supplied hydraulic pressure to therespective clutches 51 a and 51 b.

The oil feed passage 35 is able to individually communicate with eitherone of the respective oil feed passages 92 a and 92 b with operation ofthe respective solenoid valves 91 a and 91 b, and when the oil feedpassage 35 communicates with either one of the respective oil feedpassages 92 a and 92 b, a comparatively high hydraulic pressure from thesecond oil pump 32 is supplied, via either one of the respective oilfeed passages 92 a and 92 b, to either one of the engagement sidehydraulic chambers 54 a and 54 b of the respective clutches 51 a and 51b.

Specifically, when electric power is applied to the first solenoid valve91 a, communication of the oil feed passage 35 with the first oil feedpassage 92 a is cut-off, and the hydraulic pressure from the second oilpump 32 and the hydraulic pressure within the engagement side hydraulicchamber 54 a are returned to the oil pan 36 via a return oil passage 93a. On the other hand, when electric power is applied to the firstsolenoid valve 91 a, the oil feed passage 35 communicates with the firstoil feed passage 92 a, and it becomes possible to supply hydraulicpressure from the second oil pump 32 to the engagement side hydraulicchamber 54 a via the first oil feed passage 92 a.

Similarly, when electric power is applied to the second solenoid valve91 b, communication of the oil feed passage 35 with the second oil feedpassage 92 b is cut-off, and the hydraulic pressure from the second oilpump 32 and the hydraulic pressure within the engagement side hydraulicchamber 54 b are returned to the oil pan 36 via a return oil passage 93b. Moreover, when electric power is applied to the second solenoid valve91 b, the oil feed passage 35 communicates with the second oil feedpassage 92 b, and it becomes possible to supply hydraulic pressure fromthe second oil pump 32 to the engagement side hydraulic chamber 54 b viathe second oil feed passage 92 b.

A hydraulic pressure relief oil passage 96 a branches off from thedownstream side of the second oil filter 89 in the oil feed passage 35,and this hydraulic pressure relief oil passage 96 a connects via a valve95 to a hydraulic pressure relief oil passage 96 b. Moreover, ahydraulic pressure switching oil passage 98 a branches off from thedownstream side of the first oil filter 88 in the primary oil feedpassage 34, and this hydraulic pressure switching oil passage 98 aconnects via a hydraulic pressure switching valve 97 to a hydraulicpressure switching oil passage 98 b. The hydraulic pressure switchingoil passage 98 b connects to the hydraulic pressure relief valve 95, andthe hydraulic pressure relief valve 95 is operated by opening andclosing of the hydraulic pressure switching valve 97, with use of thehydraulic pressure from the primary oil feed passage 34. These oilpassages and valves are primary components that form the hydraulicpressure cut-off device 94.

With operation of the hydraulic pressure relief valve 95, the hydraulicpressure relief oil passages 96 a and 96 b establish or cut-offcommunication with each other, and when the hydraulic pressure reliefoil passages 96 a and 96 b communicate with each other, the hydraulicpressure from the second oil pump 32 is returned via the hydraulicpressure relief oil passages 96 a and 96 b to the oil pan 36, andthereby supply of the hydraulic pressure from the respective solenoidvalves 91 a and 91 b to the respective clutches 51 a and 51 b ceases. Asa result, the respective clutches 51 a and 51 b are maintained in thedisengagement state while reducing load on the second oil pump 32.

On the other hand, when communication between the hydraulic pressurerelief oil passages 96 a and 96 b is cut-of the hydraulic pressure fromthe second oil pump 32 is not returned to the oil pan 36, and hydraulicpressure is supplied to the respective solenoid valves 91 a and 91 b.With operation of the respective solenoid valves 91 a and 91 b in thisstate, hydraulic pressure is supplied to the respective clutches 51 aand 51 b, causing them to switch to the clutch engagement state.

In the above twin clutch transmission 23, when the engine of themotorcycle 1 has started and the motorcycle 1 is not travelling, both ofthe respective clutches 51 a and 51 b are maintained in thedisengagement state with actions of the hydraulic pressure cut-offdevice 94. At this time, for example if the side stand is stored (in thefull automatic mode), the shift switch is operated (in thesemi-automatic mode), or the lice, the transmission 47 is brought from aneutral state where power transmission is cut-off, for the motorcycle 1to prepare for traveling start, into a first speed state where powertransmission via the first speed gear (traveling start gear, speedchange gear pair 45 a) is possible, and for example as the enginerevolution speed increases from this state, the first clutch 51 a isbrought into an engagement state via a half-engaged clutch state tostart the motorcycle 1 traveling.

Moreover, when the motorcycle 1 is traveling, the twin clutchtransmission 23 brings only one of the respective clutches 51 a and 51 bthat corresponds to the current shift position into the engagement statewhile the other one remains in the disengagement state to carry outpower transmission via either one of the inner and outer shafts 43 and44 and any one of the respective speed change gear pairs 45 a to 45 f(or both of the clutches are brought into the engagement state and thetransmission is brought into the neutral state to standby). At thistime, the ECU 42 operation-controls the twin clutch transmission 23based on vehicle traveling information, and preliminarily creates astate where power transmission through a speed change gear pair thatcorresponds to the next shift position is possible.

Specifically, if the current shift position is on an odd speed stage (oreven speed stage), then the next shift position will be on an even speedstage (or odd speed stage), and engine output is therefore transmittedvia the first clutch 51 a (or the second clutch 51 b) to the inner shaft43 (or the outer shaft 44). At this time, the second clutch 51 b (or thefirst clutch 51 a) is in the disengagement state, and engine output isnot transmitted to the outer shaft 44 (or the inner shaft 43) (or bothof the clutches are in the engagement state, but the transmission is inthe neutral state and engine output is not transmitted).

After this, when the ECU 42 has judged that the shift-timing has beenreached, by only bringing the first clutch 51 a (or the second clutch 51b) into the disengagement state and the second clutch 51 b (or the firstclutch 51 a) into the engagement state, the transmission is switched topower transmission that uses a speed change gear pair corresponding tothe preliminarily selected next shift position. Thereby, it becomespossible to quickly and smoothly change speed without a time lag inspeed-changing or a discontinuity in power transmission (or in the caseof standing-by in the neutral state, the shift position is shifted tothe next shift position, and then the corresponding clutch is engaged).

As shown in FIG. 2 and FIG. 3, on the under section right side of thecrank case 14 and below the clutch cover 69, there is attached a body101 of the hydraulic pressure cut-off device 94 of the hydraulicpressure supply device 46. In this body 101, as shown in FIG. 9, thereare respectively formed substantially in the front-rear direction, avalve housing section 102 for the hydraulic pressure relief valve 95 anda valve housing section 103 for the hydraulic pressure switching valve97, and there are respectively formed the main sections of the hydraulicpressure relief oil passages 96 a and 96 b, and the hydraulic pressureswitching oil passages 98 a and 98 b.

Here, the hydraulic pressure cut-off device 94 is arranged on the undersection right side of the crank case 14 and below the clutch covet 69,and therefore the hydraulic pressure cut-off device 94 becomes discreetand the appearance of the engine 13 is thereby excellently maintained,while enabling suppression of lateral projection of the hydraulicpressure cut-off device 94. As a result the cover structure issimplified and the banking angle for the motorcycle 1 is ensured. Theline GL in FIG. 3 denotes the ground surface for when the vehicle bodyhas banked to just before the exhaust pipe 17 extending under the engine13 in the front-rear direction comes in contact with the ground surface.Since the body 101 of the hydraulic pressure cut-off device 94 is awayfrom the ground surface, protection of the hydraulic pressure cut-offdevice 94 is enhanced.

As shown in FIG. 9, the hydraulic pressure relief valve 95 has, in frontof a rod shaped main body, first and second pistons 104 and 105, and isfitted within a valve housing section 102 while allowing itself toreciprocate forward and backward. In the valve housing section 102, onthe front side of the first piston 104 and on the rear side of thesecond piston 105, there are respectively formed a relief side hydraulicchamber 106 and a returning side hydraulic chamber 107.

Also making reference to FIG. 3, on the vehicle width direction innerside of the rear section of the body 101 in the hydraulic pressurecut-off device 94, there is arranged the second oil filter 89 having acylindrical shape along the left-right direction. In the rear section ofthe body 101 of the hydraulic pressure cut-off device 94, there isintegrally formed a cover 101 a that covers, from the vehicle widthdirection outer side, a housing section for the second oil filter, inthe crank case 14.

The engine oil discharged from the second oil pump 32 travels throughthe second oil filter 89 from the outer circumferential side thereof tothe center section thereof to be filtered, and is then pressure-fedthrough a communicating section 108 a on the upper side of the cover 101a to the upstream side of the oil feed passage 35. The oil feed passage35 extends upward from the communicating section 108 a and reaches therespective solenoid valves 91 a and 91 b arranged on the clutch case 25(refer to FIG. 2 and FIG. 3).

Here, the respective solenoid valves 91 a and 91 b are arranged on thesame side as the twin clutch 26 and the hydraulic pressure cut-offdevice 94, that is, on the right side of the engine, and thereby thehydraulic pressure supply passages thereto can be simplified.

As shown in FIG. 18, the respective solenoid valves 91 a and 91 b may bearranged on the same side as the twin clutch 26 and the hydraulicpressure cut-off device 94, that is, on the right side of the engine andon the rear side of the clutch case 25, and in this case it is alsopossible, as with the above mentioned case, to simplify the hydraulicpressure supply passages.

Moreover, as shown in FIG. 19, the respective solenoid valves 91 a and91 b are arranged on the same side as and in the vicinity of the twinclutch 26 and the hydraulic pressure cut-off device 94, and thereby itis possible to further simplify the hydraulic pressure supply passages.Also the respective solenoid valves 91 a and 91 b axe integrallyprovided with the hydraulic pressure cut-off device 94, thereby enablingreduction in the number of components and assembly steps. FIG. 20 showsa side view of a motorcycle for the case where the solenoid valves 91 aand 91 b are arranged as shown in FIG. 19.

Referring to FIG. 5 and FIG. 9, the hydraulic pressure relief oilpassage 96 a is formed so as to reach from the inner side of the cover101 a to the valve housing section 102 for the hydraulic pressure reliefvalve 95, and the hydraulic pressure relief oil passage 96 b is formedso as to reach from the valve housing section 102 to the oil pan 36.

On the other hand, the hydraulic pressure switching oil passage 98 a isformed so as to reach from a communicating section 108 c with theprimary oil feed passage 34 and through the returning side hydraulicchamber 107, to the valve housing section 103 for the switching valve97, and the hydraulic pressure switching oil passage 98 b is formed soas to reach from the valve housing section 103 to the relief sidehydraulic chamber 106.

The hydraulic pressure switching valve 97 is a normally open typesolenoid valve that opens the hydraulic pressure switching oil passages98 a and 98 b when electric power is not applied, and that cuts off thehydraulic pressure switching passages 98 a and 98 b when electric poweris applied.

When electric power is not applied to this hydraulic pressure switchingvalve 97, part of the hydraulic pressure from the first oil pump 31 issupplied to the returning side hydraulic chamber 107 and is alsosupplied to the relief side hydraulic chamber 106 though the valvehousing section 103. The forward biasing force with respect to thehydraulic pressure relief valve 95 due to the hydraulic pressuresupplied to the relief side hydraulic chamber 106 is greater than thebackward biasing force with respect to the hydraulic pressure reliefvalve 95 due to the hydraulic pressure supplied to the returning sidehydraulic chamber 107, and when the hydraulic pressure is supplied tothe relief side hydraulic chamber 106, the hydraulic pressure reliefvalve 95 moves forward within the valve housing section 102. At thistime, the hydraulic pressure relief oil passages 96 a and 96 b areopened, and the hydraulic pressure from the second oil pump 32 isreturned to the oil pan 36.

On the other hand, when electric power is applied to the hydraulicpressure switching valve 97, the hydraulic pressure switching oilpassages 98 a and 98 b are cut-off, and supply of the hydraulic pressurefrom the first oil pump 31 to the relief side hydraulic chamber 106ceases. Consequently, the hydraulic pressure within the returning sidehydraulic chamber 107 causes the hydraulic pressure relief valve 95 tomove backward and the hydraulic pressure relief oil passages 96 a and 96b are cutoff and it becomes possible to supply hydraulic pressure to therespective solenoid valves 91 a and 91 b without having the hydraulicpressure from the second oil pump 32 returned to the oil pan 36.

The hydraulic pressure cut-off device 94 is operation-controlled by theECU 42 so that when starting the engine (when a starting switch ST(refer to FIG. 5) is operated), it opens the hydraulic pressure reliefoil passages 96 a and 96 b and returns the engine oil discharged fromthe second oil pump 32 to the oil pan 36 (returns the hydraulicpressure), and when the engine has started (after complete explosion,and after engine revolution speed has stabilized at an idling revolutionspeed), it cuts off the hydraulic pressure relief oil passages 96 a and96 b to enable supply of feed hydraulic pressure to the twin clutch 26.Start of traveling may be disabled when the side stand is pulled out, byopening the hydraulic pressure relief oil furnace 96.

That is to say, since the twin clutch 26 has a large capacity, and therotation torque required at the time of engine start, and the load onthe second oil pump 32 is high, then when starting the engine (inparticular when the temperature is low), the respective clutches 51 aand 51 b are in the disengagement state and the pressure-boost operationof the second oil pump 32 is suppressed. As a result an increase infriction is suppressed to reduce the cranking load, and the startabilityof the engine is improved. Also miniaturization and weight reduction ofthe starter motor 27 and a battery (not shown in the drawing) isachieved.

Instead of having the configuration such that engine hydraulic pressureis added to both sides of the hydraulic pressure relief valve 95 asdescribed above, the construction may be such that engine hydraulicpressure is given to one side and a spring reactive force is given tothe other side. Moreover, as shown with chain lines on the right side inFIG. 9, there may be provided an operating mechanism 109 that operatesthe hydraulic pressure relief valve 95 with other external forces (anelectronic actuator, manual operation, or the like). Furthermore, it isalso possible to carry out a, control for cutting off feed hydraulicpressure to the twin clutch 26 with signals from the ECU 42 and so forthat times other than at the time of engine start (for example, when theside stand is pulled out as mentioned above, the vehicle topples over, akill-switch is turned OFF, or the like).

As shown in FIG. 6, on the inner side of the clutch cover 69 there arearranged first, second, and third pipes 111, 112 and 113 spanningbetween this clutchcover 69 and the right end section of the main shaft28 (inner shaft 43). The respective pipes 111, 112, and 113 are arrangedcoaxially with the main shaft 28, and are arranged in order from theinner circumferential side of first, second, and third, so as to besuperposed while having a predetermined gap therebetween.

Inside the right side section of the inner shaft 43 there is formed aright hollow section 114 that expands the diameter thereof roughly inthree steps towards the right. The right hollow section 114 is separatedby a dividing wall, from the primary oil feed passage 71 that reachesfrom the left end opening thereof in the inner shaft 43 to the secondclutch 51 b vicinity, and into this right hollow section 114 there areinserted from the right end opening thereof; the left side section ofthe respective pipes 111, 112, and 113.

The left side outer circumference of the first pipe 111 is oil-tightlyretained in the left side inner circumference of the right hollowsection 114 via a sealing member 111 a. The left side outercircumference of the second pipe 112 is oil-tightly retained in theintermediate section inner circumference of the right hollow section 114via a sealing member 112 a. The left side outer circumference of thethird pipe 113 is oil-tightly retained in the right side innercircumference of the right hollow section 114 via a sealing member 113a.

Each right end section of the respective pipes 111, 112, and 113 isrespectively oil-tightly inserted and retained in ring shaped holders111 b, 112 b, and 113 b. On the right end section of each of the pipes111, 112, and 113 there is respectively formed a flange. On the rightend section of the first pipe 111, the flange is supported in a state ofbeing gripped between the holder 111 b and the right outer wall 69 a ofthe clutch cover 69. Moreover, the right end section of the second pipe112 is such that the flange is supported in a state of being grippedbetween the holder 111 b and the holder 112 b, and the right end sectionof the third pipe 113 is such that the flange is supported in a state ofbeing gripped between the holder 112 b and the holder 113 b. The holder113 b having the third pipe 113 inserted therethrough is fixed with abolt on the right outer wall 69 a of the clutch cover 69 from the innerside of the case, and thereby the respective holders 111 b, 112 b, and113 b and the respective pipes 111, 112, and 113 are fixed on the clutchcover 69.

A space within the first pipe 111 and ring-shaped spaces formed betweenthe respective pipes 111, 112, and 113 form a plurality of in-shaft oilpassages 115, 116, and 117 coaxially superposed within the main shaft28.

Specifically, the space within the first pipe 111 functions as the firstin-shaft oil passage 115, while the right end section thereofcommunicates with the first oil feed passage 92 a connected to theclutch center position of the clutch cover 69, and the left end sectionthereof communicates with the engagement side hydraulic chamber 54 b ofthe second clutch 51 b via an engagement side oil passage 115 a thatpasses through the inner and outer shafts 43 and 44 and the clutchcenter 57 b substantially in the clutch radial direction.

Moreover, the space between the first pipe 111 and the second pipe 112functions as the second in-shaft oil passage 116, while the right endsection thereof communicates with an in-cover primary oil feed passage71 a formed within the clutch cover 69, and the left end section thereofcommunicates with the disengagement side hydraulic chamber 55 a of thefirst clutch 51 a via a disengagement side oil passage 116 a that passesthrough the inner shaft 43 and the clutch center 57 a substantially inthe clutch radial direction. Hydraulic pressure from the first oil pump31 is supplied to the in-cover primary oil feed passage 71 a.

Furthermore, the space between the second pipe 112 and the third pipe113 functions as the third in-shaft oil passage 117, while the right endsection thereof communicates with the second oil feed passage 92 bconnected to a position on the clutch cover 69 offset from the clutchcenter, and the left end section thereof communicates with theengagement side hydraulic chamber 54 a of the first clutch 51 a via anengagement side oil passage 117 a that passes through the inner shaft 43and the clutch center 57 a substantially in the clutch radial direction.

Moreover, the primary oil feed passage 71 in the inner shaft 43 is suchthat the right end section thereof communicates with the disengagementside hydraulic chamber 55 b of the second clutch 51 b via adisengagement side oil passage 118 a that passes through the inner andouter shafts 43 and 44 and the clutch center 57 b substantially in theclutch radial direction.

Here, the respective in-shaft oil passages 115, 116, and 117 on theright side of the inner shaft 43 are such that the capacity (sectionalarea) of the second in-shaft oil passage 116, in which a comparativelylow hydraulic pressure acts, is smaller than the capacity of otherin-shaft oil passages 115 and 117, in which a comparatively highhydraulic pressure acts. Similarly, the capacity of each of thedisengagement side oil passages 116 a and 118 a is smaller than thecapacity of the respective engagement side oil passages 115 a and 117 a.

As shown in FIG. 10, on the left side of the upper section of themission case 22 of the engine 13, there is arranged the drivingmechanism 39 of the gear shift device 41.

Also making reference to FIG. 11A and FIG. 11B, the driving mechanism 39is such that it includes: a pin gear 121 coaxially fixed on the left endsection of the shift drum 24 a of the change mechanism 24; a worm barrelcam 122 that engages with this pin gear 121; and an electric motor 124that gives rotational driving force to this barrel cam 122 via a relaygear shaft 123, and the shift drum 24 a is rotated by drive of theelectric motor 124 to thereby change the speed change stages of thetransmission 47.

The electric motor 124 is arranged such that the rotational drive axisC4 thereof is along the front-rear direction, and a driving shaft 125thereof projects towards the rear side. On the tip end section outercircumference of the driving shaft 125 there is formed a driving gear126, and this driving gear 126 meshes with a first relay gear 127 a ofthe relay gear shaft 123. A second relay gear 127 b of this relay gearshaft 123 meshes with a driven gear 128 on the front end section of thebarrel cam 122. The barrel cam 122 has the rotational axis C5 parallelto the axis C4 of the electric motor 124, and on the front section outercircumference thereof there are formed cam grooves 129. The respectiveearn grooves 129 connect with each other so as to form a substantiallysingle (or plurality of) thread groove, and part of a plurality of pins121 a projecting on the pin gear 121 engages with these cam grooves 129.

The pin gear 121 is such that the plurality of pins 121 a at equalintervals in the circumferential direction on the left side of the diskshaped main body thereof project in parallel with the shift drum 24 a.The rotational axis C5 of the barrel cam 122 is arranged perpendicularto the rotational axis C6 along the left-right direction in the pin gear121 (shift drum 24 a). The upper section of the pin gear 121 overlaps onthe front section of the barrel cam 122 when seen in side view, and therespective pins 121 a positioned on the upper section of the pin gear121 respectively engage with the respective cam grooves 129 on the frontsection outer circumference of this barrel cam 122. At least one pair ofeach cam groove 129 and each pin 121 a needs to engage with each other.

When the electric motor 124 is driven with control of the ECU 42, andthe barrel cam 122 has rotated once in the normal rotation direction(arrow CW direction in FIG. 12A and FIG. 12B), each cam groove 129 isdisplaced to the rear by only one line (single pitch) in the arrangementdirection thereof (front-rear direction), causing the pin gear 121 andthe shift drum 24 a to rotate in the shift up direction (arrow UPdirection in FIG. 11A) by only an angle that corresponds to the singlepitch. The rotational angle of the shift drum 24 a at this timecorresponds to the angle for shifting up the speed change stage of thetransmission 47 by only one speed stage.

Similarly, when the electric motor 124 is driven and the barrel cam 122has rotated once in the reverse rotation direction (arrow CCW directionin FIG. 12A and FIG. 12B), each cam groove 129 is displaced to the frontby only a single pitch, causing the pin gear 121 and the shift drum 24 ato rotate in the shift down direction (arrow DN direction in FIG. 11A)by only an angle that corresponds to the single pitch. The rotationalangle of the shift drum 24 a at this time corresponds to the angle forshifting down the speed change stage of the transmission 47 by only onespeed stage.

The transmission 47 can establish a state where power transmission ispossible respectively in: the current shift position (shift position inwhich power transmission is actually carried out via the twin clutch26); and in a shift position on the side shifted-up or shifted-down byone speed stage from this shift position (shift position in which powertransmission is cut-off via the twin clutch 26) (that is to say, inshift positions of the respective even speed stages and odd speedstages), except for the neutral state.

In such a transmission 47, if a shift-up by one speed stage isperformed, then it is brought into a state where power transmission ispossible respectively in the current shift position and in a shiftposition on the side shifted up by one speed stage. If a shift down byone speed stage is performed, then it is brought into a state wherepower transmission is possible respectively in the current shiftposition and in a shift position on the side shifted down by one speedstage. Which of the respective shift positions to be used by thetransmission 47 to perform actual power transmission is switched,depending on which clutch the twin clutch 26 brings into an engagementstate.

As shown in FIG. 13B, each of the respective cam grooves 129 includes aholding range 129 a in which a position in the barrel cam shaftdirection (arrangement direction of each cam groove 129) is heldconstant, and a variable range 129 b in which the position in the barrelcam shaft direction gradually changes. In a state where each of the pins121 a is engaged in the holding range 129 a of each cam groove 129, thepin gear 121 and the shift drum 24 a do not rotate even if the barrelcam 122 rotates, and in a state where each of the pins 121 a is engagedin the variable range 129 a of the cam groove 129, the pin gear 121 andthe shift drum 24 a rotate in the shift-up direction or in the shiftdown direction according to rotation of the barrel cam 122.

The holding range 129 a and the variable range 129 b in each cam groove129 are smoothly connected via a curve section 129 c. The curve sections129 c of the respective cam grooves 129 are arranged in an arc shapealong the circumferential direction of the pin gear 121 (arrangementdirection of the respective pins 121 a). As a result, when the barrelcam 122 rotates the pin gear 121, the respective pins 121 a smoothly andsimultaneously enter from one of the ranges to another of the ranges ofthe respective cam grooves 129. Therefore rotation of the shift drum 24a becomes gentle and smooth, and the load on the pins 121 a and the camgrooves 129 may also be reduced.

As shown in FIG. 11A, FIG. 12A, and FIG. 12B, on the rear section outercircumference of the barrel cam 122, there are provided two switch cams131 lined up in the front-rear direction. Moreover, for example, on theleft side of each switch cam 131, there is provided a first switch 133or a second switch 134, to the cam surface of which a switching piecefaces. These switch cams 131 and the sensors 133 and 134 form the sensorS1 that detects the rotational position of the barrel cam 122.

The respective switch cams 131 have substantially the same shape whenseen in the barrel cam axial direction, and on the outer circumferencethereof there is formed a cam surface. The cam surface of each switchcam 131 has a reference surface 131 a in a cylindrical shape coaxialwith the barrel cam 122 and a similarly cylinder-shaped lift surface 131b having the diameter thereof expanded from that of the referencesurface 131 a, and the cam surface is formed with both of these smoothlyconnected surfaces. The respective switch cams 131 are arranged so thatthe lift surface formation ranges thereof mutually create apredetermined phase difference in the barrel cam rotational direction.Specifically, with respect to the switch cam 131 for the first switch133, the switch cam 131 for the second switch 134 is arranged so as tobe displaced by only a predetermined angle in the CCW direction.

The respective switches 133 and 134 detect the rotational status of thebarrel cam 122 by advancing/retracting the switching pieces thereof in acase where the switching piece faces the reference surface 131 a of eachswitch cam 131 (in a case where the respective switches 133 and 134 areturned OFF), and in a case where the switching piece faces the liftsurface 131 b of each switch earn 131 (in a case where the respectiveswitches 133 and 134 are turned ON). The respective switches 133 and 134are arranged so as to be in the same phase in the barrel cam rotationaldirection.

FIG. 14 is a diagram showing ON and OFF of the respective first andsecond switches 133 and 134 with respect to rotational angle of thebarrel cam 122. A region where the lift surface 131 b of each switch cam131 faces a point “a”, which is a detection position of the respectiveswitches 133 and 134 (the region where the respective switches 133 and134 are turned ON), signifies a stop region where the respective pins121 a of the pin gear 121 are present within the holding range 129 a ofthe respective cam grooves 129 and the driving torque of the electricmotor 124 is zero (refer to FIG. 15B).

At this time, by setting the transmission 47 so that it is brought intoa state of having completed a speed changing operation, even a slightdisplacement in the rotational position of the barrel cam 122 does notaffect the shift positions, and even if the driving torque of theelectric motor 124 is zero, rotation of the shift drum 24 a isrestricted so as to be held in a predetermined shift position. The angleof the stop region is set to be equal to or greater than an anglethrough which the barrel cam 122 inertially rotates when the drivingtorque of the electric motor 124 is zero.

On the other hand, a region where the reference surface 131 a of eachswitch cam 131 faces the point “a” (the region where the respectiveswitches 133 and 134 are turned OFF) signifies a feed region where therespective pins 121 a of the pin gear 121 are present within thevariable range 129 b of the respective cam grooves 129 of the barrel cam122 and the electric motor 124 is driven at normal torque (maximumtorque±Tmax set by the system) (refer to FIG. 15B).

At this time the transmission 47 is in the process of the speed changingoperation, and the shift drum 24 a rotates in the shift up direction orin the shift down direction according to the rotation of the barrel cam122. The angle of the feed region corresponds to the formation angle ofthe variable range 129 b of the respective cam grooves 129 in the barrelcam 122.

A region where one of the lift surfaces 131 b of the respective switchcams 131 faces the point “a” (the region where one of the respectiveswitches 133 and 134 is turned ON) signifies a CW or CCW correctionregion where the respective pins 121 a of the pin gear 121 are presentin the vicinity of the end section of the holding range 129 a of therespective cam grooves 129 of the barrel cam 122 and the electric motor124 is driven at a small torque (the minimum torque±Tmin that overcomesthe friction of the system) (refer to FIG. 15B).

Specifically, in the CCW correction region where only the second switch134 having the phase displaced in the CCW direction of the barrel cam122 is turned ON, correction is performed by driving the electric motor124 at a minimum reverse rotation torque (−Tmin) for rotating the barrelcam 122 at a low torque in the CCW direction to set the stop region.Moreover, in the CW correction region where only the first switch 133having the phase displaced in the CW direction of the barrel cam 122 isturned ON, correction is performed by driving the electric motor 124 ata minimum normal rotation torque (+Tmin) for rotating the barrel cam 122at a low torque in the CW direction to set the stop region.

As shown in FIG. 16, the single switch cam 131 is provided in the barrelcam 122 to allow the cam surface of the switch cam 131 to face the twoswitches 133 and 134 so as to have the phase difference in the barrelcam rotational direction, and this enables the similar control asdescribed above while reducing the number of switch cams. Moreover, theswitches 133 and 134 are not limited to being formed as mechanicalcontact type switches, and may be formed as switches that use electricor magnetic power, or non-contact type switches.

FIG. 17A and FIG. 17B are graphs showing changes in the rotational angleand angular velocity of the shift drum 24 a with respect to therotational angle of the barrel cam 122. In the case where, as seen inthe present embodiment, the respective ranges 129 a and 129 b of therespective cam grooves 129 of the barrel cam 122 are smoothly connectedvia the curve section 129 c (refer to FIG. 17A), changes in rotationalangle of the shift drum 24 a become smoother, and the rise-up inrotational angle velocity of the shift drum 24 a before and after thevariable range 129 b becomes smoother, compared to the case where therespective cam grooves 129 are connected so as to be bent between therespective ranges 129 a and 129 b but not via the curve section 129 c(refer to FIG. 17B).

Therefore, the inertial torque of the shift drum 24 a at the time ofshift-up and shift-down is suppressed, and the load exerted on therespective components of the mechanism can be suppressed. Moreover, whenthe barrel cam 122 has rotated once, the rotational position thereofbecomes the initial position of the shift position on the side one stageshifted up or shifted down, and it is possible to continuously performspeed change operations from this state.

As described above, the gear shift device 41 in the above embodimentthat is used in the twin clutch transmission 23 of the engine 13, isprovided with: the shift drum 24 a that changes a speed change stage ofthe twin clutch transmission 23 according to a rotational position aboutan axis; the electric motor 124 having a driving shaft substantiallyorthogonal to this shift drum 24 a; the worm shaped barrel earn 122 thatis arranged parallel to the driving shaft of the electric motor 124 andthat has a plurality of cam grooves 129 on the outer circumference; andthe pin gear 121 that is coaxially fixed on the shift drum 24 a and thathas a plurality of pins 121 a on the outer circumference. At least apair of each pin 121 a of the pin gear 121 and each cam groove 129 ofthe barrel cam 122 are engaged with each other, and the shift drum 24 ais rotated by the electric motor 124 via the barrel cam 122 and the pingear 121, to thereby change the speed change stage of the twin clutchtransmission 23, and there is further provided a pair of switch cams 131that detect the rotational position of the barrel cam 122, and first andsecond switches 133 and 134 that correspond to these.

According to this configuration, by detecting the rotational position ofthe shift drum 24 a from the rotational position of the worm shapedbarrel cam 122, the rotational position of the shift drum can 24 a bedetected efficiently without using an expensive sensor.

Moreover, in the above gear shift device 41, by providing the switchcams 131 integrally with the outer circumference of the barrel cam 122,and arranging the two mutually independent switches 133 and 134corresponding to these switch cams 131 with a predetermined phasedifference in the barrel cam rotational direction, it is possible toaccurately detect if the barrel cam 122 has rotated to the shift up sideor the shift down side, or if shift up or shift down has been completed.

The present invention is not limited to the above embodiment, and may beapplied to various types of internal combustion engines such as; asingle cylinder engine, a V-type engine, and a longitudinal type enginehaving the crankshaft axis along the front-rear direction. Moreover, thepresent invention may also be applied to a three- or four-wheeledsaddle-ride type vehicle, or to a scooter type vehicle having alow-floor footstool section, in addition to motorcycles.

The configuration in the above embodiment is an example of the presentinvention, and may also be applied to a four-wheeled passenger vehicle.Furthermore, various kinds of modifications may be made withoutdeparting from the scope of the invention.

INDUSTRIAL APPLICABILITY

It is possible to provide a gear shift device in which the rotationalposition of the shift drum can be detected efficiently while keepingcost down.

1. A gear shift device used in a transmission of an engine, comprising:a shift drum that changes a speed change stage of the transmissionaccording to a rotational position about an axis; an actuator having adriving shaft substantially orthogonal to the shift drum; a worm shapedbarrel cam that is arranged parallel to the driving shaft of theactuator and that has a plurality of cam grooves on an outercircumference thereof; and a wheel gear that is coaxially fixed on theshift drum and that has a plurality of pins on an outer circumferencethereof, wherein: at least a pair of each pin of the wheel gear and eachcam groove of the barrel cam are engaged with each other, and the shiftdrum is rotated by the actuator via the barrel cam and the wheel gear,to thereby change the speed change stage of the transmission; and thegear shift device further comprises a detection device that detects arotational position of the barrel cam; and the detection device has acam provided integral with an outer circumference of the barrel cam. 2.The gear shift device according to claim 1, wherein the detection devicehas two independent sensors corresponding to the cam, which are arrangedwith a predetermined phase difference along a rotational direction ofthe barrel cam.